Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The rabbit lacrimal gland secretes retinol bound to a 20-21 kDa protein. To test the hypothesis that this protein might be retinol-binding protein (RBP) we probed lacrimal gland for RBP mRNA and lacrimal gland fluid for RBP. A rabbit RBP cDNA clone was used to probe rabbit and rat lacrimal gland RNA using RNase protection analysis. The lacrimal gland contains RBP mRNA at a level 0.1 to 0.03% of that observed in the liver. This RBP mRNA was identical to that observed in the liver based on RNase protection analysis, Northern blot analysis and primer extension analysis. The RBP mRNA levels in the lacrimal gland were not altered by the retinol status of the rabbits. We analysed lacrimal gland fluid for RBP by immunoblotting using a monoclonal antibody that recognizes rat, human and rabbit RBP. A single protein band from the rabbit lacrimal fluid bound the antibody, and this protein comigrated with human RBP which also bound the antibody. We conclude that the lacrimal gland contains RBP mRNA and that the lacrimal gland synthesizes and secretes RBP into the lacrimal gland fluid. This is the first demonstration that an extrahepatic tissue containing RBP mRNA synthesizes and secretes the protein in vivo.
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PMID:The lacrimal gland synthesizes retinol-binding protein. 133 54

Transgenic mice carrying a liver-specific promoter fused to a nuclear-targeted lacZ reporter gene were generated. Three separate lines of mice showed liver expression in the adult and no expression elsewhere in the animal. These results show that a 1.7 kb 5'-flanking region in the retinol-binding protein gene contains necessary and sufficient transcriptional signals for expression in adult livers. A fourth line (R197) did not express the transgene in the liver; instead, constitutive lacZ expression was seen during postimplantation stages of development from Day 9.5 onwards and appeared to be associated with segmented structures including somites, branchial arches, and hindbrain rhombomeres until late fetal stages. The beta-galactosidase positive cells in R197 were later seen to give rise to facial and flank musculature, and to other region-specific subpopulations of the jaws, neocortex, and brain stem. Northern blot analysis for the host retinol-binding protein RNA transcript did not show overlapping tissue expression with the reporter gene and suggests that transgenic phenotype seen in segmented embryonic structures of R197 and other extra-hepatic sites is from novel cis-acting transcriptional specificity. RNase protection assays of the R197 mRNA indicate that the lacZ sequences are appropriately transcribed downstream of the RBP canonical TATA box, even though the RBP promoter is itself silent. This result would suggest host flanking sequences with enhancer activity may have either activated the lacZ reporter gene or cooperated with the RBP promoter to create novel region-specific transcription. Breeding experiments have so far failed to produce offsprings that are homozygous for the transgene, and mating of transgenic F1 siblings routinely produce reduced litter sizes. Embryos that are homozygous for the transgene appear to be unable to survive beyond the egg cylinder stages of development. Thus, disruption of the host genome by insertional mutation appears to be manifest at an earlier stage than when position-effect expression of the transgene is first apparent. These experiments demonstrate that the component parts of a transgene may be subject to differential activation or suppression by host genomic flanking sequences and that even a strong, tissue-specific promoter may be overridden by host genes.
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PMID:Liver-specific and position-effect expression of a retinol-binding protein-lacZ fusion gene (RBP-lacZ) in transgenic mice. 206 Jul 5

The gene encoding the mouse cellular retinoic acid-binding protein (CRABP) has been isolated from a mouse genomic library and its structure has been determined. This gene spans approximately 10.5 kb and consists of four exons encoding 24, 59, 38, and 16 amino acid residues, respectively. This gene structure is very similar to the structures of other related genes belonging to the same protein family such as the human cellular retinol-binding protein, the rat cellular retinol-binding protein II, the rat fatty acid-binding protein, and the mouse adipocyte P2 protein. The site for transcription initiation has been mapped to the 93rd nucleotide upstream from the translation initiation codon ATG using both primer extension and RNase protection assays. From the DNA sequence, the promoter of the CRABP gene resembles those found in the "housekeeping" genes in that it is very G/C rich, lacks a TATA box, and contains multiple copies of the sequence GGGCGG. The deduced amino acid sequence of the translated region is identical to the amino acid sequence of the known bovine CRABP, and the DNA sequence of the transcribed region from the mouse gene shows approximately 78% homology to that of the bovine cDNA.
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PMID:Molecular cloning and transcriptional mapping of the mouse cellular retinoic acid-binding protein gene. 217 50

A study was conducted to determine the levels of cellular retinol-binding protein (CRBP) mRNA and protein in various tissues of the rat, to explore relationship between CRBP mRNA and protein levels in different tissues, and to examine the effects of changes in retinol nutritional status on the tissue distribution and levels of CRBP mRNA. Previous studies have shown that tissue CRBP protein levels are reduced in totally retinoid-deficient rats, but are otherwise minimally affected by changes in retinoid status. Three groups of male rats were compared: normal controls, retinoid-deficient, and retinol-repleted deficient rats. CRBP mRNA levels were measured by RNase protection assay and CRBP protein levels by radioimmunoassay in seven tissues. High levels of both CRBP mRNA and CRBP protein were found in the proximal epididymis, kidney, and liver; lower levels were seen in lung, testis, spleen, and small intestine. Tissue CRBP mRNA and protein levels were highly correlated (P less than 0.01) with each other. Retinoid deficiency did not alter the levels of CRBP mRNA found in the proximal epididymis, kidney, and liver. In contrast, CRBP mRNA levels in the lung, testis, spleen, and small intestine were reduced substantially in retinoid-deficient rats, to values that were only 23% to 50% of the corresponding values in the tissues of control rats. After oral repletion with retinol (4-18 h earlier), CRBP mRNA levels for these latter four tissues were found to have risen to control or near-control levels. The suggestion is raised that retinol repletion may have directly induced the expression of the CRBP gene in these particular tissues.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cellular retinol-binding protein messenger RNA levels in normal and retinoid-deficient rats. 238 Jun 30

P19 embryonal carcinoma (EC) cells can be induced to differentiate in vitro into a variety of cell types by treatment with different concentrations of retinoic acid (RA). A study was conducted to explore the regulation of expression of the genes for cellular retinoic acid-binding protein (CRABP) and cellular retinol-binding protein (CRBP) in P19 cells induced to differentiate by RA. For each retinoid-binding protein, both the level of specific mRNA and of immunoreactive protein were measured, respectively, by RNase protection assay and by a specific RIA. Dramatic increases in CRABP and CRBP were seen, at both the mRNA and protein levels, during the RA-induced differentiation. CRBP induction differed from that of CRABP in several major ways. 1) Induction of CRBP occurred at lower concentrations of RA (10(-9) M) than did that of CRABP (10(-8)-10(-7) M). 2) CRBP induction was an early response (within 3 h) to RA treatment, whereas CRABP induction occurred at a later time (12-24 h). 3) Induction of CRABP mRNA by RA was blocked by the protein synthesis inhibitor cycloheximide, whereas induction of CRBP mRNA was not. 4) Several differentiation inducers were tested for their effects on the expression of CRABP and CRBP in P19 cells. CRBP induction occurred with a wider spectrum of inducers than did that of CRABP. 5) In addition, the induction of CRABP and CRBP mRNAs by RA was examined in six different cell lines, including three EC lines. CRBP induction occurred in a wider spectrum of cell lines than did that of CRABP. The induction of CRABP in EC cells seems, in general, to correlate with their differentiation into neuron-like cells. Taken together, our results suggest that CRBP induction may be a direct response to RA and represent a general event in RA-induced cell differentiation, whereas CRABP induction may be an indirect response and represent a later event restricted to only certain differentiation pathways. CRBP may be an early response gene induced by RA.
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PMID:Regulation of the cellular retinoid-binding proteins and their messenger ribonucleic acids during P19 embryonal carcinoma cell differentiation induced by retinoic acid. 254 63

Retinol (vitamin A alcohol), which plays an important role in the differentiation of epithelia, can be transferred to chromatin in vitro. Rat liver chromatin can accept retinol in a specific and saturable manner only when the retinol is presented as a complex with cellular retinol-binding protein (CRBP). A partial characterization of the nuclear components responsible for accepting retinol is reported here. A preparation of solubilized chromatin isolated from liver nuclei was able to accept retinol from its complex with CRBP as described previously for nuclei and chromatin. The binding of retinol to chromatin was noncovalent. However, chromatin prepared from nuclei which were incubated with DNase I or micrococcal nuclease did not accept retinol specifically. Chromatin in the form of mono and dinucleosomes also did not accept retinol. However, treatment of nuclei with RNase did not affect the specific binding of retinol. Furthermore, it has been found that retinol was not transferred to purified double or single stranded DNA. These results are interpreted to indicate that the transfer of retinol to specific nuclear binding sites requires a higher order of chromatin structure than that occurring in nucleosome preparations.
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PMID:Partial characterization of nuclear binding sites for retinol delivered by cellular retinol binding protein. 298 10

Studies were conducted to explore in rats the role of retinol in the regulation of the synthesis and secretion of retinol-binding protein (RBP) by the visceral yolk sac compared to the liver. Previous studies have shown that in retinol deficiency, hepatic RBP secretion is specifically inhibited, whereas hepatic RBP synthesis rate is unchanged. Retinol-depleted, retinoic acid-supplemented female rats were mated, and maternal liver, fetal liver, and visceral yolk sac were obtained at 14 days of gestation (retinol-depleted group). A group of identically treated, retinol-depleted rats were repleted with retinol on the 14th day of gestation, and the same tissues were collected 6 h later (retinol-repleted group). Normal female rats were used as controls. RBP was assayed by radioimmunoassay and RBP mRNA levels by RNase protection assay using a rat RBP cDNA clone. RBP levels in the visceral yolk sac were elevated 10-fold in the retinol-depleted as compared to the control rats and had declined to near normal values in the retinol-repleted animals. The relative levels of RBP mRNA in the visceral yolk sac were very similar in all three groups of rats. Thus, as in the liver, in the visceral yolk sac retinol deficiency inhibits RBP secretion without altering RBP mRNA levels. In the visceral yolk sac, as in the liver, retinol status appears to regulate RBP secretion specifically, without affecting the rate of RBP biosynthesis.
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PMID:Retinol-binding protein synthesis and secretion by the rat visceral yolk sac. Effect of retinol status. 334 35

The effects of different intravenous nutritional regimens on a number of biochemical indices of nutritional status were studied during the 8-day period following severe trauma. The inclusion of large amounts of amino acids (high nitrogen (N) was shown to greatly improve N balance over an isocaloric regimen containing no amino acids (O g N). The concentration of serum albumin, transferrin, prealbumin, and retinol-binding protein all fell during the study period in both patient groups, whereas the serum concentrations of acute phase reactants and of ribonuclease increased in the two groups. The sum of plasma levels of branched-chain amino acids and the essential amino acids was increased to a greater extent in the high N group. These amino acid totals and the ratio of glycine/valine showed a significant correlation with N balance in this group. Despite the marked difference in N balance, 3-methylhistidine excretion was increased but equal in the two nutritional groups, suggesting an increased rate of muscle protein breakdown in both groups, which appears not to be influenced by amino acid nutrition. It is concluded that N balance can be significantly improved in the immediate posttrauma period by provision of amino acids together with energy substrates. None of the biochemical variables measured, with the exception of plasma levels of essential amino acids, reflected these marked differences in N balance.
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PMID:Biochemical changes associated with severe trauma. 677 18

A retinol dehydrogenase, RoDH(1), which recognizes holo-cellular retinol-binding protein (CRBP) as substrate, has been cloned, expressed, and identified as a short-chain dehydrogenase/reductase (Chai, X., Boerman, M. H. E. M., Zhai, Y., and Napoli, J. L. (1995) J. Biol. Chem. 270, 3900-3904). This work reports the cloning and expression of a cDNA encoding a RoDH isozyme, RoDH(II). The predicted amino acid sequence verifies RoDH(II) as a short-chain dehydrogenase/reductase, 82% identical with RoDH(I). RoDH(II) recognized the physiological form of retinol as substrate, CRBP, with a Km of 2 mM. Similar to microsomal RoDH and RoDH(I), RoDH(II) had higher activity with NADP rather than NAD, was stimulated by ethanol and phosphatidyl choline, was not inhibited by the medium-chain alcohol dehydrogenase inhibitor 4-methylpyrazole, but was inhibited by phenylarsine oxide and the short-chain dehydrogenase/reductase inhibitor carbenoxolone. Northern blot analysis detected RoDH(I) and RoDH(II) mRNA only in rat liver, but RNase protection assays revealed RoDH(I) and RoHD(II) mRNA in kidney, lung, testis, and brain. These data indicate that short-chain dehydrogenases/reductase isozymes expressed tissue-distinctively catalyze the first step of retinoic acid biogenesis from the physiologically most abundant substrate, CRBP.
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PMID:Cloning of a cDNA for a second retinol dehydrogenase type II. Expression of its mRNA relative to type I. 749 45

Fifteen various serum and urine parameters were evaluated as indicators of renal alterations induced by lead in 82 male workers of a battery plant chronically exposed to lead (median of blood lead concentration: 2.03 mumol/l). The control group comprised 44 non-exposed healthy volunteers (0.34 mumol/l). High-molecular-mass proteins (transferrin, immunoglobulin G (IgG), (albumin)) were determined in urine as markers of glomerular integrity; low-molecular-weight proteins and parenchymal enzymes (alpha 1-microglobulin, beta 2-microglobulin, retinol-binding protein, lysozyme, ribonuclease, N-acetyl-beta-D-glucosaminidase (NAG), alanine aminopeptidase (AAP), alkaline phosphatase (AP), gamma-glutamyltransferase (GGT)) as indicators of changes in the proximal tubule; Tamm-Horsfall glycoprotein and kallikrein as markers of the distal tubule. There was a positive correlation between tubular indicators and blood lead concentration as well as the erythrocyte protoporphyrin (EPP). About 30% of the lead-exposed workers showed an increased excretion of alpha 1-microglobulin, NAG, ribonuclease, and/or Tamm-Horsfall protein, whereas the glomerular indicators remained unchanged. The combined determination of NAG and alpha 1-microglobulin in urine could be helpful in the early detection of lead-induced changes in the nephron.
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PMID:Changed excretion of urinary proteins and enzymes by chronic exposure to lead. 752 73


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